Neural processing device and method for using shared page table thereof

ABSTRACT

A neural processing device and a method for using shared page table thereof are provided. The neural processing device including at least one neural processor, a shared memory shared by the at least one neural processor, and a global interconnection configured to exchange data between the at least one neural processor and the shared memory, comprises at least one processing unit each of which included in each of the at least one neural processor and configured to provide logical addresses, a memory management unit configured to receive and translate the logical addresses into physical addresses, and a physical memory accessible by the physical addresses, wherein the memory management unit comprises a shared page table that has translation information between the logical addresses and the physical addresses and is shared by at least one process with each other.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2022-0068955 filed on Jun. 07, 2022, now KR Patent No. 10-2509472 registered on Mar. 08, 2023, and KR Patent Application No. 10-2023-0025123 filed on Feb. 24, 2023, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The disclosure relates to a neural processing device and a method for using a shared page table thereof. More particularly, the disclosure relates to a neural processing device that increases a hit rate of a translation lookaside buffer by sharing a page table in a multi-process environment and a method for using the shared page table thereof.

BACKGROUND

For the last few years, artificial intelligence technology has been the core technology of the Fourth Industrial Revolution and the subject of discussion as the most promising technology worldwide. The biggest problem with artificial intelligence technology is computing performance. For artificial intelligence technology to realize a level of human learning ability, reasoning ability, perceptual ability, natural language implementation ability, etc., it is of the utmost importance to process a large amount of data quickly.

The central processing unit (CPU) or graphics processing unit (GPU) of off-the-shelf computers was used to implement deep-learning training and inference in early artificial intelligence, but these components had limitations in their ability to perform the tasks of deep-learning training and inference with high workloads. Thus, neural processing units (NPUs) that are structurally specialized for deep learning tasks have received a lot of attention.

Since a general multi-process environment accesses separate memory areas from each other, it is of course possible to perform translation between logical addresses and physical addresses via different page tables. However, if a page table is shared by multiple processes, efficiency can be increased by continuously using the same page table even after processes change.

The description set forth in the background section should not be assumed to be prior art merely because it is set forth in the background section. The background section may describe aspects or embodiments of the disclosure.

SUMMARY

Aspects of the disclosure provide a neural processing device with improved efficiency via a shared page table.

Aspects of the disclosure provide a method for using a shared page table of a neural processing device with improved efficiency via the shared page table.

According to some aspects of the disclosure, a neural processing device including at least one neural processor, a shared memory shared by the at least one neural processor, and a global interconnection configured to exchange data between the at least one neural processor and the shared memory, comprises at least one processing unit each of which included in each of the at least one neural processor and configured to provide logical addresses, a memory management unit configured to receive and translate the logical addresses into physical addresses, and a physical memory accessible by the physical addresses, wherein the memory management unit comprises a shared page table that has translation information between the logical addresses and the physical addresses and is shared by at least one process with each other.

According to some aspects, the shared page table comprises a page table entry (PTE) having recorded therein starting positions of the physical memory corresponding to the logical addresses, and mapping type data having recorded therein mapping types of the logical addresses.

According to some aspects, the mapping types comprise a shared type shared by the at least one process or a private type not shared by the at least one process.

According to some aspects, a logical address of the shared type allows all of the at least one process to access a same shared physical page in the physical memory.

According to some aspects, context data of a context to which the at least one process belongs are stored in the shared physical page.

According to some aspects, logical addresses of the private type allow each of the at least one process to access different private physical pages in the physical memory.

According to some aspects, the private physical pages are arranged to be consecutive to each other.

According to some aspects, each of the private physical pages stores input/output data of each of the at least one process.

According to some aspects, the at least one process comprises first to fourth processes, the first and second processes operate concurrently with each other, the third and fourth processes operate concurrently with each other, and the first and second processes and the third and fourth processes do not operate concurrently with each other.

According to some aspects, the mapping types further comprise an intermediate type shared by some of the at least one process.

According to some aspects, logical addresses of the intermediate type allow the first and third processes to access a same first intermediate physical page in the physical memory, and the second and fourth processes to access a same second intermediate physical page in the physical memory.

According to some aspects, the first and second intermediate physical pages are arranged consecutively.

According to some aspects, the memory management unit further comprises a translation lookaside buffer configured to store physical addresses for recently used logical addresses.

According to some aspects, the translation lookaside buffer translates a stored logical address into a physical address for the stored logical address if a logical address that is same as the stored logical address is received, and translates a received logical address into a physical address for the received logical address by referring to the shared page table if a logical address that is not same as the stored logical address is received.

According to some aspects, each of the at least one neural processor comprises at least one neural core, and each of the at least one neural core comprises one of the at least one processing unit, an L0 memory configured to transmit and receive data to and from the one of the at least one processing unit, and a load store unit configured to load data into the L0 memory and transmit data from the L0 memory.

According to some aspects, the load store unit comprises the translation lookaside buffer.

According to some aspects of the disclosure, a method for using a shared page table of a neural processing device, comprises accessing, by the neural processing device, a physical memory by referring to the shared page table in a first process, and accessing, by the neural processing device, the physical memory by referring to the shared page table in a second process if there is process switching from the first process to the second process.

According to some aspects, accessing the physical memory comprises checking a PTE and a mapping type from the shared page table, and accessing a physical page according to the PTE if the mapping type is a shared type.

According to some aspects, accessing the physical memory comprises checking a PTE and a mapping type from the shared page table, and accessing a physical page by correcting the PTE with a process ID as an offset if the mapping type is a private type.

According to some aspects, accessing the physical memory comprises checking a PTE and a mapping type from the shared page table, and calculating a final offset according to a process ID if the mapping type is an intermediate type and accessing a physical page by correcting the PTE with the final offset.

Aspects of the disclosure are not limited to those mentioned above and other objects and advantages of the disclosure that have not been mentioned can be understood by the following description and will be more clearly understood according to embodiments of the disclosure. In addition, it will be readily understood that the objects and advantages of the disclosure can be realized by the means and combinations thereof set forth in the claims.

The neural processing device and the method for using a shared page table thereof of the disclosure can increase the storage efficiency of the physical memory by not individually storing data commonly used in each process.

Further, since there is no need to replace the page table when a process switching occurs, the hit rate of the translation lookaside buffer can be kept high without being reduced.

In addition to the foregoing, the specific effects of the disclosure will be described together while elucidating the specific details for carrying out the embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for illustrating a neural processing system in accordance with some embodiments of the disclosure;

FIG. 2 is a block diagram for illustrating the neural processing device of FIG. 1 ;

FIG. 3 is a block diagram for illustrating the neural core SoC of FIG. 2 ;

FIG. 4 is a structural diagram for illustrating the global interconnection of FIG. 3 ;

FIG. 5 is a block diagram for illustrating the neural processor of FIG. 3 ;

FIG. 6 is a diagram for illustrating a hierarchical structure of a neural processing device in accordance with some embodiments of the disclosure;

FIG. 7 is a block diagram for illustrating the neural core of FIG. 5 in detail;

FIG. 8 is a block diagram for illustrating the LSU of FIG. 7 in detail;

FIG. 9 is a block diagram for illustrating the processing unit of FIG. 7 ;

FIG. 10 is a block diagram for illustrating the L0 memory of FIG. 7 in detail;

FIG. 11 is a block diagram for illustrating the local memory bank of FIG. 10 ;

FIG. 12 is a block diagram for illustrating the structure of the neural processing device of FIG. 1 in detail;

FIG. 13 is a block diagram for illustrating the memory reconstruction of the neural processing system of FIG. 1 ;

FIG. 14 is a block diagram showing an example of the memory reconstruction of the neural processing system of FIG. 1 ;

FIG. 15 is an enlarged block diagram of a portion A of FIG. 13 ;

FIG. 16 is a diagram for illustrating the first memory bank of FIG. 15 in detail;

FIG. 17 is a block diagram for illustrating a software hierarchy of a neural processing device in accordance with some embodiments of the disclosure;

FIG. 18 is a block diagram for illustrating multi-processes of a neural processing system in accordance with some embodiments of the disclosure;

FIG. 19 is a block diagram for illustrating address translation of a neural processing system in accordance with some embodiments of the disclosure;

FIG. 20 is a block diagram for illustrating allocation of physical pages of the physical memory of FIG. 19 ;

FIG. 21 is a block diagram for illustrating allocation of physical pages of a physical memory of a neural processing system in accordance with some embodiments of the disclosure;

FIG. 22 is a block diagram for illustrating allocation of physical pages of a physical memory of a neural processing system in accordance with some embodiments of the disclosure;

FIG. 23 is a conceptual diagram for illustrating the mapping type data of FIG. 19 ;

FIG. 24 is a conceptual diagram for illustrating deep learning calculations performed by a neural processing device in accordance with some embodiments of the disclosure;

FIG. 25 is a conceptual diagram for illustrating training and inference operations of a neural network of a neural processing device in accordance with some embodiments of the disclosure;

FIG. 26 is a flowchart for illustrating a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure;

FIG. 27 is a flowchart for illustrating accessing the physical memory of FIG. 26 ;

FIG. 28 is a flowchart for illustrating a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure;

FIG. 29 is a flowchart for illustrating a method of allocating physical pages of a neural processing device in accordance with some embodiments of the disclosure; and

FIG. 30 is a flowchart for illustrating a method of allocating physical pages of a neural processing device in accordance with some embodiments of the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The terms or words used in the disclosure and the claims should not be construed as limited to their ordinary or lexical meanings. They should be construed as the meaning and concept in line with the technical idea of the disclosure based on the principle that the inventor can define the concept of terms or words in order to describe his/her own embodiments in the best possible way. Further, since the embodiment described herein and the configurations illustrated in the drawings are merely one embodiment in which the disclosure is realized and do not represent all the technical ideas of the disclosure, it should be understood that there may be various equivalents, variations, and applicable examples that can replace them at the time of filing this application.

Although terms such as first, second, A, B, etc. used in the description and the claims may be used to describe various components, the components should not be limited by these terms. These terms are used only for the purpose of distinguishing one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the scope of the disclosure. The term ‘and/or’ includes a combination of a plurality of related listed items or any item of the plurality of related listed items.

The terms used in the description and the claims are merely used to describe particular embodiments and are not intended to limit the disclosure. Singular expressions include plural expressions unless the context explicitly indicates otherwise. In the application, terms such as “comprise,” “have,” “include”, “contain,” etc. should be understood as not precluding the possibility of existence or addition of features, numbers, steps, operations, components, parts, or combinations thereof described herein. Terms such as a “circuit” or “circuitry”, refers to a circuit in hardware but may also refer to a circuit in software.

Unless otherwise defined, the phrases “A, B, or C,” “at least one of A, B, or C,” or “at least one of A, B, and C” may refer to only A, only B, only C, both A and B, both A and C, both B and C, all of A, B, and C, or any combination thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by those of ordinary skill in the art to which the disclosure pertains.

Terms such as those defined in commonly used dictionaries should be construed as having a meaning consistent with the meaning in the context of the relevant art, and are not to be construed in an ideal or excessively formal sense unless explicitly defined in the disclosure.

In addition, each configuration, procedure, process, method, or the like included in each embodiment of the disclosure may be shared to the extent that they are not technically contradictory to each other.

Hereinafter, a neural processing device in accordance with some embodiments of the disclosure will be described with reference to FIGS. 1 to 25 .

FIG. 1 is a block diagram for illustrating a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 1 , a neural processing system NPS in accordance with some embodiments may include a first neural processing device 1, a second neural processing device 2, and an external interface 3.

The first neural processing device 1 may be a device that performs calculations using an artificial neural network. The first neural processing device 1 may be, for example, a device specialized in performing tasks of deep learning calculations. However, the embodiment is not limited thereto.

The second neural processing device 2 may be a device having the same or similar configuration as the first neural processing device 1. The first neural processing device 1 and the second neural processing device 2 may be connected to each other via the external interface 3 and share data and control signals.

Although FIG. 1 shows two neural processing devices, the neural processing system NPS in accordance with some embodiments is not limited thereto. That is, in a neural processing system NPS in accordance with some embodiments, three or more neural processing devices may be connected to each other via the external interface 3. Also, conversely, a neural processing system NPS in accordance with some embodiments may include only one neural processing device.

In this case, the first neural processing device 1 and the second neural processing device 2 may each be a processing device other than the neural processing device. That is, the first neural processing device 1 and the second neural processing device 2 may each be a graphics processing unit (GPU), a central processing unit (CPU), and other types of processing units as well. In the following, the first neural processing device 1 and the second neural processing device 2 will be described as neural processing devices for convenience.

FIG. 2 is a block diagram for illustrating the neural processing device of FIG. 1 .

Referring to FIG. 2 , a first neural processing device 1 may include a neural core SoC 10, a CPU 20, an off-chip memory 30, a first non-volatile memory interface 40, a first volatile memory interface 50, a second non-volatile memory interface 60, and a second volatile memory interface 70.

The neural core SoC 10 may be a system on a chip device. The neural core SoC 10 can be an artificial intelligence calculation device and may be an accelerator. The neural core SoC 10 may be, for example, any one of a graphics processing unit (GPU), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC). However, the embodiment is not limited thereto.

The neural core SoC 10 may exchange data with other external calculation devices via the external interface 3. Further, the neural core SoC 10 may be connected to the non-volatile memory 31 and the volatile memory 32 via the first non-volatile memory interface 40 and the first volatile memory interface 50, respectively.

The CPU 20 may be a control device that controls the system of the first neural processing device 1 and executes program calculations. The CPU 20 is a general-purpose calculation device and may have low efficiency in performing simple parallel calculations that are frequently used in deep learning. Accordingly, there can be high efficiency by performing calculations in deep learning inference and training tasks by the neural core SoC 10.

The CPU 20 may exchange data with other external calculation units via the external interface 3. Further, the CPU 20 may be connected to the non-volatile memory 31 and the volatile memory 32 via the second non-volatile memory interface 60 and the second volatile memory interface 70, respectively.

The off-chip memory 30 may be a memory disposed outside the chip of the neural core SoC 10. The off-chip memory 30 may include a non-volatile memory 31 and a volatile memory 32.

The non-volatile memory 31 may be a memory that continuously retains stored information even if electric power is not supplied. The non-volatile memory 31 may include, for example, at least one of Read-Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Alterable ROM (EAROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM) (e.g., NAND Flash memory, NOR Flash memory), Ultra-Violet Erasable Programmable Read-Only Memory (UVEPROM), Ferroelectric Random-Access Memory (FeRAM), Magnetoresistive Random-Access Memory (MRAM), Phase-change Random-Access Memory (PRAM), silicon-oxide-nitride-oxide-silicon (SONOS), Resistive Random-Access Memory (RRAM), Nanotube Random-Access Memory (NRAM), magnetic computer storage devices (e.g., hard disks, diskette drives, magnetic tapes), optical disc drives, or 3D XPoint memory. However, the embodiment is not limited thereto.

The volatile memory 32 may be a memory that continuously requires electric power to retain stored information, unlike the non-volatile memory 31. The volatile memory 32 may include, for example, at least one of Dynamic Random-Access Memory (DRAM), Static Random-Access Memory (SRAM), Synchronous Dynamic Random-Access Memory (SDRAM), or Double Data Rate SDRAM (DDR SDRAM). However, the embodiment is not limited thereto.

Each of the first non-volatile memory interface 40 and the second non-volatile memory interface 60 may include, for example, at least one of Parallel Advanced Technology Attachment (PATA), Small Computer System Interface (SCSI), Serial Attached SCSI (SAS), Serial Advanced Technology Attachment (SATA), or PCI Express (PCIe). However, the embodiment is not limited thereto.

Each of the first volatile memory interface 50 and the second volatile memory interface 70 may be, for example, at least one of SDR (Single Data Rate), DDR (Double Data Rate), QDR (Quad Data Rate), or XDR (eXtreme Data Rate, Octal Data Rate). However, the embodiment is not limited thereto.

FIG. 3 is a block diagram for illustrating the neural core SoC of FIG. 2 .

Referring to FIGS. 2 and 3 , the neural core SoC 10 may include at least one neural processor 1000, a shared memory 2000, direct memory access (DMA) 3000, a non-volatile memory controller 4000, a volatile memory controller 5000, and a global interconnection 6000.

The neural processor 1000 may be a calculation device that directly performs calculation tasks. If there exist neural processors 1000 in plurality, calculation tasks may be assigned to respective neural processors 1000. The respective neural processors 1000 may be connected to each other via the global interconnection 6000.

The shared memory 2000 may be a memory shared by multiple neural processors 1000. The shared memory 2000 may store data of each neural processor 1000. In addition, the shared memory 2000 may receive data from the off-chip memory 30, store the data temporarily, and transfer the data to each neural processor 1000. The shared memory 2000 may also receive data from the neural processor 1000, store the data temporarily, and transfer the data to the off-chip memory 30 of FIG. 2 .

The shared memory 2000 may be required to be a relatively high-speed memory. Accordingly, the shared memory 2000 may include, for example, an SRAM. However, the embodiment is not limited thereto. That is, the shared memory 2000 may include a DRAM as well.

The shared memory 2000 may be a memory corresponding to the SoC level, i.e., level 3 (L3). Accordingly, the shared memory 2000 may also be defined as an L3 shared memory.

The DMA 3000 may directly control the movement of data without the need for the neural processor 1000 to control the input/output of data. Accordingly, the DMA 3000 may control the data movement between memories, thereby minimizing the number of interrupts of the neural processor 1000.

The DMA 3000 may control the data movement between the shared memory 2000 and the off-chip memory 30. Via the authority of the DMA 3000, the non-volatile memory controller 4000 and the volatile memory controller 5000 may perform the movement of data.

The non-volatile memory controller 4000 may control the task of reading from or writing onto the non-volatile memory 31. The non-volatile memory controller 4000 may control the non-volatile memory 31 via the first non-volatile memory interface 40. In this case, the non-volatile memory controller 4000 may be referred to as a non-volatile memory controller circuit, but for the sake of convenience, the terms are unified as a non-volatile memory controller. In addition, the non-volatile memory controller 4000 may be implemented as a circuit or circuitry.

The volatile memory controller 5000 may control the task of reading from or writing onto the volatile memory 32. Further, the volatile memory controller 5000 may perform a refresh task of the volatile memory 32. The volatile memory controller 5000 may control the volatile memory 32 via the first volatile memory interface 50. Likewise, the volatile memory controller 5000 may be referred to as a volatile memory controller circuit, but for the sake of convenience, the terms are unified as a volatile memory controller. In addition, the volatile memory controller 5000 may be implemented as a circuit or circuitry.

The global interconnection 6000 may connect the at least one neural processor 1000, the shared memory 2000, the DMA 3000, the non-volatile memory controller 4000, and the volatile memory controller 5000 to one another. In addition, the external interface 3 may also be connected to the global interconnection 6000. The global interconnection 6000 may be a path through which data travels between the at least one neural processor 1000, the shared memory 2000, the DMA 3000, the non-volatile memory controller 4000, the volatile memory controller 5000, and the external interface 3.

The global interconnection 6000 may transmit not only data but also control signals and may transmit a signal for synchronization. That is, in the neural processing device in accordance with some embodiments, each neural processor 1000 may directly transmit and receive a synchronization signal, instead of a separate control processor managing the synchronization signal. Accordingly, it is possible to preclude the latency of the synchronization signal generated by the control processor.

In other words, if there exist neural processors 1000 in plurality, there may be dependencies of individual tasks in which the task of one neural processor 1000 needs to be finished before the next neural processor 1000 can start a new task. The end and start of these individual tasks can be checked and/or coordinated via a synchronization signal, and in conventional techniques, a control processor performed the reception of such a synchronization signal and an instruction to start a new task.

However, as the number of neural processors 1000 increases and task dependencies are designed more complicatedly, the number of requests and instructions for this synchronization task can increase exponentially. Therefore, the latency resulting from each request and instruction can greatly reduce the efficiency of tasks.

Accordingly, in the neural processing device in accordance with some embodiments, each neural processor 1000, instead of the control processor, may directly transmit a synchronization signal to another neural processor 1000 according to the dependency of a task. In this case, several neural processors 1000 can perform the synchronization tasks in parallel as compared with the method managed by the control processor, thereby minimizing the latency due to synchronization.

In addition, the control processor needs to perform the task scheduling of the neural processors 1000 according to a task dependency, and the overhead of such scheduling may increase significantly as the number of neural processors 1000 increases. Accordingly, in the neural processing device, in accordance with some embodiments, the scheduling task is also performed by the individual neural processors 1000, and thus, the performance of the neural processing device can be improved without resulting in an additional scheduling burden.

FIG. 4 is a structural diagram for illustrating the global interconnection of FIG. 3 .

Referring to FIG. 4 , the global interconnection 6000 may include a data channel 6100, a control channel 6200, and an L3 sync channel 6300.

The data channel 6100 may be a dedicated channel for transmitting data. Through the data channel 6100, the at least one neural processor 1000, the shared memory 2000, the DMA 3000, the non-volatile memory controller 4000, the volatile memory controller 5000, and the external interface 3 may exchange data with one another.

The control channel 6200 may be a dedicated channel for transmitting control signals. Through the control channel 6200, the at least one neural processor 1000, the shared memory 2000, the DMA 3000, the non-volatile memory controller 4000, the volatile memory controller 5000, and the external interface 3 may exchange control signals with one another.

The L3 sync channel 6300 may be a dedicated channel for transmitting synchronization signals. Through the L3 sync channel 6300, the at least one neural processor 1000, the shared memory 2000, the DMA 3000, the non-volatile memory controller 4000, the volatile memory controller 5000, and the external interface 3 may exchange synchronization signals with one another.

The L3 sync channel 6300 may be set as a dedicated channel inside the global interconnection 6000, and thus, may not overlap with other channels and transmit synchronization signals quickly. Accordingly, the neural processing device in accordance with some embodiments does not require new wiring work and may smoothly perform the synchronization task by using the global interconnection 6000.

FIG. 5 is a block diagram for illustrating the neural processor of FIG. 3 .

Referring to FIGS. 3 to 5 , a neural processor 1000 may include at least one neural core 100, an L2 shared memory 400, a local interconnection 200, and an L2 sync path 300.

The at least one neural core 100 may share and perform the tasks of the neural processor 1000. The number of neural cores 100 may be, for example, eight. However, various embodiments are not limited thereto. FIG. 5 illustrates that a plurality of neural cores are included in the neural processor 1000, but various embodiments are not limited thereto. That is, the neural processor 1000 may be configured with only one neural core.

The L2 shared memory 400 may be a memory shared by the neural cores 100 in the neural processor 1000. The L2 shared memory 400 may store data of each neural core 100. In addition, the L2 shared memory 400 may receive data from the shared memory 2000 of FIG. 3 , store them temporarily, and transfer them to each neural core 100. On the contrary, the L2 shared memory 400 may also receive data from the neural core 100, store them temporarily, and transfer them to the shared memory 2000 of FIG. 3 .

The L2 shared memory 400 may be a memory corresponding to the neural processor level, i.e., level 2 (L2). The L3 shared memory, i.e., the shared memory 2000 may be shared by the neural processors 1000, and the L2 shared memory 400 may be shared by the neural cores 100.

The local interconnection 200 may connect the at least one neural core 100 and the L2 shared memory 400 to each other. The local interconnection 200 may be a path through which data travels between the at least one neural core 100 and the L2 shared memory 400. The local interconnection 200 may be connected and transmit data to the global interconnection 6000 of FIG. 3 .

The L2 sync path 300 may connect the at least one neural core 100 and the L2 shared memory 400 to each other. The L2 sync path 300 may be a path through which synchronization signals of the at least one neural core 100 and the L2 shared memory 400 travel.

The L2 sync path 300 may be formed physically separately from the local interconnection 200. In the case of the local interconnection 200, sufficient channels may not be formed therein, unlike the global interconnection 6000. In such a case, the L2 sync path 300 may be formed separately so that the synchronization signal can be transmitted quickly and without any delay. The L2 sync path 300 may be used for synchronization performed at a level one step lower than that of the L3 sync channel 6300 of the global interconnection 6000.

FIG. 6 is a diagram for illustrating a hierarchical structure of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 6 , the neural core SoC 10 may include at least one neural processor 1000. Each neural processor 1000 may transmit data to each other via the global interconnection 6000.

The neural processors 1000 may each include at least one neural core 100. The neural core 100 may be a processing unit optimized for deep learning calculation tasks. The neural core 100 may be a processing unit corresponding to one operation of a deep learning calculation task. In other words, a deep learning calculation task can be represented by a sequential or parallel combination of multiple operations. The neural cores 100 may each be a processing unit capable of processing one operation, and may be a minimum calculation unit that can be considered for scheduling from the viewpoint of a compiler.

The neural processing device in accordance with the embodiment may configure the scales of the minimum calculation unit, considered from the viewpoint of compiler scheduling and the hardware processing unit to be the same, so that fast and efficient scheduling and calculation tasks can be performed.

That is, if the processing units into which hardware can be divided are too large compared to calculation tasks, inefficiency of the calculation tasks may occur in driving the processing units. Conversely, it is not appropriate to schedule a processing unit that is a unit smaller than an operation, which is the minimum scheduling unit of the compiler, every time since a scheduling inefficiency may occur and hardware design costs may increase.

Therefore, by adjusting the scales of the scheduling unit of the compiler and the hardware processing unit to be similar in the embodiment, it is possible to simultaneously satisfy the rapid scheduling and efficient execution of calculation tasks without wasting hardware resources.

FIG. 7 is a block diagram for illustrating the neural core of FIG. 5 in detail.

Referring to FIG. 7 , the neural core 100 may include a load/store unit (LSU) 110, an L0 memory 120, a weight buffer 130, an activation LSU 140, an activation buffer 150, and a processing unit 160.

The LSU 110 may receive at least one of data, a control signal, or a synchronization signal from the outside via the local interconnection 200 and the L2 sync path 300. The LSU 110 may transmit at least one of the data, the control signal, or the synchronization signal received to the L0 memory 120. Similarly, the LSU 110 may transfer at least one of the data, the control signal, or the synchronization signal to the outside via the local interconnection 200 and the L2 sync path 300. In this case, the LSU 110 may be referred to as an LSU circuit, but for the sake of convenience, the terms are unified as an LSU. In addition, the LSU 110 may be implemented as a circuit or circuitry.

FIG. 8 is a block diagram for illustrating the LSU of FIG. 7 .

Referring to FIG. 8 , the LSU 110 may include a local memory load unit (LMLU) 111 a, a local memory store unit (LMSU) 111 b, a neural core load unit (NCLU) 112 a, a neural core store unit (NCSU) 112 b, a load buffer LB, a store buffer SB, a load (LD) engine 113 a, a store (ST) engine 113 b, and a translation lookaside buffer (TLB) 114.

The local memory load unit 111 a, the local memory store unit 111 b, the neural core load unit 112 a, the neural core store unit 112 b, the load engine 113 a, and the store engine 113 b may be referred to respectively as a local memory load circuit, a local memory store circuit, a neural core load circuit, a neural core store circuit, a load engine circuit, and a store engine circuit. However, for the sake of convenience, the terms are respectively unified as a local memory load unit, a local memory store unit, a neural core load unit, a neural core store unit, a load engine, and a store engine. In addition, the local memory load unit 111 a, the local memory store unit 111 b, the neural core load unit 112 a, the neural core store unit 112 b, the load engine 113 a, and the store engine 113 b may each be implemented as a circuit or circuitry.

The local memory load unit 111 a may fetch a load instruction for the L0 memory 120 and issue the load instruction. When the local memory load unit 111 a provides the issued load instruction to the load buffer LB, the load buffer LB may sequentially transmit memory access requests to the load engine 113 a according to the inputted order.

Further, the local memory store unit 111 b may fetch a store instruction for the L0 memory 120 and issue the store instruction. When the local memory store unit 111 b provides the issued store instruction to the store buffer SB, the store buffer SB may sequentially transmit memory access requests to the store engine 113 b according to the inputted order.

The neural core load unit 112 a may fetch a load instruction for the neural core 100 and issue the load instruction. When the neural core load unit 112 a provides the issued load instruction to the load buffer LB, the load buffer LB may sequentially transmit memory access requests to the load engine 113 a according to the inputted order.

In addition, the neural core store unit 112 b may fetch a store instruction for the neural core 100 and issue the store instruction. When the neural core store unit 112 b provides the issued store instruction to the store buffer SB, the store buffer SB may sequentially transmit memory access requests to the store engine 113 b according to the inputted order.

The load engine 113 a may receive the memory access request and retrieve data via the local interconnection 200. At this time, the load engine 113 a may quickly find the data by using a translation table of a physical address and a virtual address that has been used recently in the translation lookaside buffer 114. If the virtual address of the load engine 113 a is not in the translation lookaside buffer 114, the address translation information may be found in another memory.

The store engine 113 b may receive the memory access request and retrieve data via the local interconnection 200. At this time, the store engine 113 b may quickly find the data by using a translation table of a physical address and a virtual address that has been used recently in the translation lookaside buffer 114. If the virtual address of the store engine 113 b is not in the translation lookaside buffer 114, the address translation information may be found in another memory.

The load engine 113 a and the store engine 113 b may send synchronization signals to the L2 sync path 300. At this time, the synchronization signal may indicate that the task has been completed.

Referring to FIG. 7 again, the L0 memory 120 is a memory located inside the neural core 100, and may receive all input data required for the tasks by the neural core 100 from the outside and store them temporarily. In addition, the L0 memory 120 may temporarily store the output data calculated by the neural core 100 for transmission to the outside. The L0 memory 120 may serve as a cache memory of the neural core 100.

The L0 memory 120 may transmit an input activation Act_In to the activation buffer 150 and receive an output activation Act_Out via the activation LSU 140. The L0 memory 120 may directly transmit and receive data to and from the processing unit 160, in addition to the activation LSU 140. In other words, the L0 memory 120 may exchange data with each of a processing element (PE) array 163 and a vector unit 164. The L0 memory 120 may be a memory corresponding to the level of the neural core. In this case, the L0 memory 120 may be a private memory of the neural core that is not shared.

The L0 memory 120 may transmit data such as activations or weights via a data path. The L0 memory 120 may exchange synchronization signals via an L1 sync path, which is a separate dedicated path. The L0 memory 120 may exchange synchronization signals with, for example, the LSU 110, the weight buffer 130, the activation LSU 140, and the processing unit 160 via the L1 sync path.

The weight buffer 130 may receive a weight from the L0 memory 120. The weight buffer 130 may transfer the weight to the processing unit 160. The weight buffer 130 may temporarily store the weight before transferring it.

The input activation Act_In and the output activation Act_Out may refer to input values and output values of the layers of a neural network. In this case, if there are a plurality of layers in the neural network, the output value of the previous layer becomes the input value of the next layer, and thus, the output activation Act_Out of the previous layer may be utilized as the input activation Act_In of the next layer.

The weight may refer to a parameter that is multiplied by the input activation Act_In inputted in each layer. The weight is adjusted and confirmed in the deep learning training phase, and may be used to derive the output activation Act_Out via a fixed value in the inference phase.

The activation LSU 140 may transfer the input activation Act_In from the L0 memory 120 to the activation buffer 150, and the output activation Act_Out from the activation buffer 150 to the on-chip buffer. In other words, the activation LSU 140 may perform both a load task and a store task of the activation.

The activation buffer 150 may provide the input activation Act_In to the processing unit 160 and receive the output activation Act_Out from the processing unit 160. The activation buffer 150 may temporarily store the input activation Act_In and the output activation Act_Out.

The activation buffer 150 may quickly provide the activation to the processing unit 160, in particular, the PE array 163, which has a large quantity of calculations, and may quickly receive the activation, thereby increasing the calculation speed of the neural core 100.

The processing unit 160 may be a module that performs calculations. The processing unit 160 may perform not only one-dimensional calculations but also two-dimensional matrix calculations, i.e., convolution operations. The processing unit 160 may receive an input activation Act_In, multiply it by a weight, and then add it to generate an output activation Act_Out.

FIG. 9 is a block diagram for illustrating the processing unit of FIG. 7 in detail.

Referring to FIG. 7 and FIG. 9 , the processing unit 160 may include a PE array 163, a vector unit 164, a column register 161, and a row register 162.

The PE array 163 may receive the input activation Act_In and the weight and perform multiplication on them. In this case, each of the input activation Act_In and the weight may be in the form of matrices and calculated via convolution. Through this, the PE array 163 may generate an output activation Act_Out. However, the embodiment is not limited thereto. The PE array 163 may generate any types of outputs other than the output activation Act_Out as well.

The PE array 163 may include at least one processing element (PE) 163_1. The processing elements 163_1 may be aligned with each other so that each of the processing elements 163_1 may perform multiplication on one input activation Act_In and one weight.

The PE array 163 may sum values for each multiplication to generate a subtotal. This subtotal may be utilized as an output activation Act_Out. The PE array 163 performs two-dimensional matrix multiplication, and thus, may be referred to as a 2D matrix compute unit.

The vector unit 164 may mainly perform one-dimensional calculations. The vector unit 164, together with the PE array 163, may perform deep learning calculations. Through this, the processing unit 160 may be specialized for necessary calculations. In other words, each of the at least one neural core 100 has calculation modules that perform a large amount of two-dimensional matrix multiplications and one-dimensional calculations, and thus, can efficiently perform deep learning tasks.

The column register 161 may receive a first input I1. The column register 161 may receive the first input I1, and distribute them to each column of the processing elements 163_1.

The row register 162 may receive a second input 12. The row register 162 may receive the second input 12, and distribute them to each row of the processing elements 163_1.

The first input I1 may be an input activation Act_In or a weight. The second input I2 may be a value other than the first input I1 between the input activation Act_In or the weight. Alternatively, the first input I1 and the second input I2 may be values other than the input activation Act_In and the weight.

FIG. 10 is a block diagram for illustrating the L0 memory of FIG. 7 in detail.

Referring to FIG. 10 , the L0 memory 120 may include a scheduler 121 and one or more local memory banks 122.

When data is stored in the L0 memory 120, the scheduler 121 may receive data from the load engine 113 a. In this case, the local memory bank 122 may be allocated for the data in a round-robin manner. Accordingly, data may be stored in any one of the local memory banks 122.

In contrast to this, when data is loaded from the L0 memory 120, the scheduler 121 may receive the data from the local memory bank 122 and transmit the data to the store engine 113 b. The store engine 113 b may store the data in the outside through the local interconnection 200. In this case, the scheduler 121 may be referred to as a scheduler circuit, but for the sake of convenience, the term is unified as a scheduler. In addition, the scheduler 121 may be implemented as a circuit or circuitry.

FIG. 11 is a block diagram for illustrating the local memory bank of FIG. 10 in detail.

Referring to FIG. 11 , the local memory bank 122 may include a local memory bank controller 122_1 and a local memory bank cell array 122_2.

The local memory bank controller 122_1 may manage read and write operations via the addresses of data stored in the local memory bank 122. In other words, the local memory bank controller 122_1 may manage the input/output of data as a whole.

The local memory bank cell array 122_2 may be of a structure in which cells in which data is directly stored are arranged in rows and columns. The local memory bank cell array 122_2 may be controlled by the local memory bank controller 122_1.

FIG. 12 is a block diagram for illustrating in detail the structure of the neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 12 , a neural core 101 may have a CGRA structure, unlike a neural core 100. The neural core 101 may include an instruction memory 111_1, a CGRA L0 memory 111_2, a PE array 111_3, and a load/store unit (LSU) 111_4. The PE array 111_3 may include a plurality of processing elements interconnected by a mesh style network. The mesh style network may be two-dimensional, three-dimensional, or higher-dimensional. In the CGRA, the plurality of processing elements may be reconfigurable or programmable. The interconnection between the plurality of processing elements may be reconfigurable or programmable. In some embodiments, the interconnection between the plurality of processing elements may be statically reconfigurable or programmable when the interconnection is fixed after the plurality of processing elements are configurated or programed. In some embodiments, the interconnection between the plurality of processing elements may be dynamically reconfigurable or programmable when the interconnection is reconfigurable or programmable even after the plurality of processing elements are configurated or programed.

The instruction memory 111_1 may receive and store instructions. The instruction memory 111_1 may sequentially store instructions internally, and provide the stored instructions to the PE array 111_3. In this case, the instructions may instruct the operation of first type of a plurality of processing elements 111_3 a included in each PE array 111_3.

The CGRA L0 memory 111_2 may be located inside the neural core 101, receive all input data required for tasks of the neural core 101, and temporarily store the data. In addition, the CGRA L0 memory 111_2 may temporarily store output data calculated by the neural core 101 to transmit the data to the outside. The CGRA L0 memory 111_2 may serve as a cache memory of the neural core 101.

The CGRA L0 memory 111_2 may transmit and receive data to and from the PE array 111_3. The CGRA L0 memory 111_2 may correspond to L0 (a level 0) lower than L1. In this case, the L0 memory may be a private unshared memory of the neural core 101 unlike the L2 shared memory 400. The CGRA L0 memory 111_2 may transmit a program and data, such as activation or weight, to the PE array 111_3.

The PE array 111_3 may be a module that performs calculations. The PE array 111_3 may perform not only one-dimensional calculations but also two-dimensional or higher matrix/tensor calculations. The PE array 111_3 may include the first type of the plurality of processing elements 111_3 a and a second type of a plurality of processing elements 111_3 b therein.

The first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b may be arranged in rows and columns. The first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b may be arranged in m columns. In addition, the first type of the plurality of processing elements 111_3 a may be arranged in n rows, and the second type of the plurality of processing elements 111_3 b may be arranged in 1 rows. Accordingly, the first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing element 111_3 b may be arranged in (n+1) rows and m columns.

The LSU 111_4 may receive at least one of data, a control signal, or a synchronization signal from the outside through the local interconnection 200. The LSU 111_4 may transmit at least one of the received data, the received control signal, or the received synchronization signal to the CGRA L0 memory 111_2. Similarly, the LSU 111_4 may transmit at least one of data, a control signal, or a synchronization signal to the outside through the local interconnection 200. The LSU 111_4 may be referred to as an LSU circuit, but for the sake of convenience, the terms are unified as an LSU. In addition, the LSU 111_4 may be implemented as a circuit or circuitry.

The neural core 101 may have a CGRA (Coarse Grained Reconfigurable Architecture) structure. Accordingly, in the neural core 101, each of the first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b of the PE array 111_3 may be connected to at least one of the CGRA L0 memory 111_2, the instruction memory 111_1, or the LSU 111_4, respectively. In other words, the first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b do not have to be connected to all of the CGRA L0 memory 111_2, the instruction memory 111_1, and the LSU 111_4, but may be connected to some thereof.

Further, the first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b may be different types of processing elements from each other. Accordingly, out of the CGRA L0 memory 111_2, the instruction memory 111_1, and the LSU 111_4, the elements connected to the first type of the plurality of processing elements 111_3 a and the elements connected to the second type of the plurality of processing elements 111_3 b may be different from each other.

The neural core 101 of the disclosure having a CGRA structure enables high-level parallel calculations, and since direct data exchange between the first type of the plurality of processing elements 111_3 a and the second type of the plurality of processing elements 111_3 b is possible, the power consumption may be low. In addition, by including two or more types of processing elements, optimization according to various calculation tasks may also be possible.

For example, if the first type of the plurality of processing elements 111_3 a are processing elements that perform two-dimensional calculations, the second type of the plurality of processing elements 111_3 b may be processing elements that perform one-dimensional calculations. However, the embodiment is not limited thereto.

FIG. 13 is a block diagram for illustrating memory reconfiguration of a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 13 , the neural core SoC 10 may include first to eighth processing units 160 a to 160 h and an on-chip memory OCM. Although FIG. 13 illustrates eight processing units as an example, this is merely illustrative, and the number of processing units may vary as desired.

The on-chip memory OCM may include first to eighth L0 memories 120 a to 120 h and a shared memory 2000.

The first to eighth L0 memories 120 a to 120 h may be used as private memories for the first to eighth processing units 160 a to 160 h, respectively. In other words, the first to eighth processing units 160 a to 160 h and the first to eighth L0 memories 120 a to 120 h may correspond to each other 1:1.

The shared memory 2000 may include first to eighth memory units 2100 a to 2100 h. The first to eighth memory units 2100 a to 2100 h may correspond to the first to eighth processing units 160 a to 160 h and the first to eighth L0 memories 120 a to 120 h, respectively. That is, the number of memory units may be eight, which is the same as the number of processing units and L0 memories.

The shared memory 2000 may operate in one of two kinds of on-chip memory types. In other words, the shared memory 2000 may operate in one of a L0 memory type or a global memory type. In other words, the shared memory 2000 may implement two types of logical memories with one piece of hardware.

If the shared memory 2000 is implemented in the L0 memory type, the shared memory 2000 may operate as a private memory for each of the first to eighth processing units 160 a to 160 h, just like the first to eighth L0 memories 120 a to 120 h. The L0 memory can operate at a relatively higher clock speed compared with the global memory, and the shared memory 2000 may also use a relatively higher clock speed when operating in the L0 memory type.

If the shared memory 2000 is implemented in the global memory type, the shared memory 2000 may operate as a common memory used by the first processing unit 160 a and the second processing unit 160 b together. In this case, the shared memory 2000 may be shared not only by the first to eighth processing units 160 a to 160 h but also by the first to eighth L0 memories 120 a to 120 h.

The global memory may generally use a lower clock compared with the L0 memory, but is not limited thereto. When the shared memory 2000 operates in the global memory type, the first to eighth processing units 160 a to 160 h may share the shared memory 2000. In this case, the shared memory 2000 may be connected to the volatile memory 32 of FIG. 2 via the global interconnection 6000 and may also operate as a buffer for the volatile memory 32.

At least part of the shared memory 2000 may operate in the L0 memory type, and the rest may operate in the global memory type. In other words, the entire shared memory 2000 may operate in the L0 memory type, or the entire shared memory 2000 may operate in the global memory type. Alternatively, part of the shared memory 2000 may operate in the L0 memory type, and the rest may operate in the global memory type.

FIG. 14 is a block diagram showing an example of memory reconstruction of a neural processing system in accordance with some embodiments of the disclosure.

With reference to FIGS. 13 and 14 , first, third, fifth, and seventh dedicated areas AE1, AE3, AE5, and AE7 for each of the first, third, fifth, and seventh processing units 160 a, 160 c, 160 e, and 160 g may include only the first, third, fifth, and seventh L0 memories 120 a, 120 c, 120 e, and 120 g, respectively. Further, second, fourth, sixth, and eighth dedicated areas AE2, AE4, AE6, and AE8 for each of the second, fourth, sixth, and eighth processing units 160 b, 160 d, 160 f, and 160 h may include second, fourth, sixth, and eighth L0 memories 120 b, 120 d, 120 f, and 120 h, respectively. In addition, the second, fourth, sixth, and eighth dedicated areas AE2, AE4, AE6, and AE8 may include the second, fourth, sixth, and eighth memory units 2100 b, 2100 d, 2100 f, and 2100 h. The first, third, fifth, and seventh memory units 2100 a, 2100 c, 2100 e, and 2100 g of the shared memory 2000 may be used as a common area AC.

The common area AC may be a memory shared by the first to eighth processing units 160 a to 160 h. The second dedicated area AE2 may include a second L0 memory 120 b and a second memory unit 2100 b. The second dedicated area AE2 may be an area in which the second L0 memory 120 b and the second memory unit 2100 b that are separated hardware-wise operate in the same manner and operate logically as one L0 memory. The fourth, sixth, and eighth dedicated areas AE4, AE6, and AE8 may also operate in the same manner as the second dedicated area AE2.

The shared memory 2000 in accordance with the embodiment may convert an area corresponding to each processing unit into a logical L0 memory and a logical global memory of an optimized ratio and may use them. The shared memory 2000 may perform the adjustment of this ratio at runtime.

That is, each processing unit may perform the same task in some cases, but may perform different tasks in other cases as well. In this case, the amount of the L0 memory and the amount of the global memory required for the tasks carried out by each processing unit are inevitably different each time. Accordingly, if the composition ratio of the L0 memory and the shared memory is fixedly set as in the conventional on-chip memory, there may occur inefficiency due to the calculation tasks assigned to each processing unit.

Therefore, the shared memory 2000 of the neural processing device in accordance with the embodiment may set an optimal ratio of the L0 memory and the global memory according to calculation tasks during the runtime, and may enhance the efficiency and speed of calculation.

FIG. 15 is an enlarged block diagram of a portion A of FIG. 13 .

With reference to FIGS. 13 and 15 , the shared memory 2000 may include a first L0 memory controller 122_1 a, a second L0 memory controller 122_1 b, a fifth L0 memory controller 122_1 e, a sixth L0 memory controller 122_1 f, the first to eighth memory units 2100 a to 2100 h, and a global controller 2200. Other L0 memory controllers not shown may also be included in the embodiment, but the description thereof will be omitted for convenience.

The first L0 memory controller 122_1 a, the second L0 memory controller 122_1 b, the fifth L0 memory controller 122_1 e, the sixth L0 memory controller 122_1 f, and the global controller 2200 may be referred to respectively as a first L0 memory controller circuit, a second L0 memory controller circuit, a fifth L0 memory controller circuit, a sixth L0 memory controller circuit, and a global controller circuit. However, for the sake of convenience, the terms are respectively unified as a first L0 memory controller, a second L0 memory controller, a fifth L0 memory controller, a sixth L0 memory controller, and a global controller. In addition, the first L0 memory controller 122_1 a, the second L0 memory controller 122_1 b, the fifth L0 memory controller 122_1 e, the sixth L0 memory controller 122_1 f, and the global controller 2200 may each be implemented as a circuit or circuitry.

The first L0 memory controller 122_1 a may control the first L0 memory 120 a. In addition, the first L0 memory controller 122_1 a may control the first memory unit 2100 a. Specifically, when the first memory unit 2100 a is implemented in a logical L0 memory type, the control by the first L0 memory controller 122_1 a may be performed on the first memory unit 2100 a.

The second L0 memory controller 122_1 b may control the second L0 memory 120 b. Further, the second L0 memory controller 122_1 b may control the second memory unit 2100 b. In other words, when the second memory unit 2100 b is implemented in the logical L0 memory type, the control by the first L0 memory controller 122_1 a may be performed on the second memory unit 2100 b.

The fifth L0 memory controller 122_1 e may control the fifth L0 memory 120 e. Further, the fifth L0 memory controller 122_1 e may control the fifth memory unit 2100 e. In other words, when the fifth memory unit 2100 e is implemented in the logical L0 memory type, the control by the fifth L0 memory controller 122_1 e may be performed on the fifth memory unit 2100 e.

The sixth L0 memory controller 122_1 f may control the sixth L0 memory 120 f. Further, the sixth L0 memory controller 122_1 f may control the sixth memory unit 2100 f. In other words, when the sixth memory unit 2100 f is implemented in the logical L0 memory type, the control by the sixth L0 memory controller 122_1 f may be performed on the sixth memory unit 2100 f.

The global controller 2200 may control all of the first to eighth memory units 2100 a to 2100 h. Specifically, the global controller 2200 may control the first memory unit 2100 a to the eighth memory unit 2100 h when the first to eighth memory units 2100 a to 2100 h each operate logically in the global memory type (i.e., when they do not operate logically in the L0 memory type).

In other words, the first to eighth memory units 2100 a to 2100 h may be controlled by the first to eighth L0 memory controllers 122_1 a to 122_1 h, respectively, or may be controlled by the global controller 2200, depending on what type of memory they are logically implemented.

If the L0 memory controllers including the first, second, fifth, and sixth L0 memory controllers 122_1 a, 122_1 b, 122_1 e, and 122_1 f control the first to eighth memory units 2100 a to 2100 h, respectively, the first to eighth L0 memory controllers 122_1 a to 122_1 h control the first to eighth memory units 2100 a to 2100 h in the same manner as the first to eighth L0 memories 120 a to 120 h, and thus, can control them as the private memory of the first to eighth processing units 160 a to 160 h. Accordingly, the first to eighth memory units 2100 a to 2100 h may operate at clock frequencies corresponding to the clock frequencies of the first to eighth processing units 160 a to 160 h.

The L0 memory controllers including the first L0 memory controller 122_1 a, the second L0 memory controller 122_1 b, the fifth L0 memory controller 122_1 e, and the sixth L0 memory controller 122_1 f may each include the LSU 110 of FIG. 7 .

If the global controller 2200 controls at least one of the first to eighth memory units 2100 a to 2100 h, respectively, then the global controller 2200 may control the first to eighth memory units 2100 a to 2100 h as the global memory of the first to eighth processing units 160 a to 160 h, respectively. Accordingly, at least one of the first to eighth memory units 2100 a to 2100 h may operate at a clock frequency independent of the clock frequencies of the first to eighth processing units 160 a to 160 h, respectively. In some embodiments, if the global controller 2200 controls the i-th memory unit among the first to eighth memory units 2100 a to 2100 h, the global controller 2200 may control the i-th memory unit as the global memory of the i-th processing unit, and the i-th memory unit may operate at a clock frequency independent of the clock frequency of the i-th processing unit. However, the embodiment is not limited thereto.

The global controller 2200 may connect the first to eighth memory units 2100 a to 2100 h to the global interconnection 6000 as shown and described in accordance with FIG. 3 . The first to eighth memory units 2100 a to 2100 h may exchange data with an off-chip memory 30 as shown and described in accordance with FIG. 2 via the control of the global controller 2200 or may respectively exchange data with the first to eighth L0 memories 120 a to 120 h.

Each of the first to eighth memory units 2100 a to 2100 h may include at least one memory bank. The first memory unit 2100 a may include at least one first memory bank 2110 a. The first memory banks 2110 a may be one or more areas obtained by dividing the first memory unit 2100 a into certain sizes. The first memory banks 2110 a may all be memory devices of the same size. However, the embodiment is not limited thereto. FIG. 15 shows that four memory banks are included in one memory unit.

Similarly, the second, fifth, and sixth memory units 2100 b, 2100 e, and 2100 f may include at least one second, fifth, and sixth memory banks 2110 b, 2110 e, and 2110 f, respectively.

In the following, the description will be made based on the first memory banks 2110 a and the fifth memory banks 2110 e, which may be the same as other memory banks including the second and sixth memory banks 2110 b and 2110 f.

The first memory banks 2110 a may each operate logically in the L0 memory type or operate logically in the global memory type. In this case, the first memory banks 2110 a may operate independently of the other memory banks in the first memory unit 2100 a. However, the embodiment is not limited thereto.

If each memory bank operates independently, the first memory unit 2100 a may include a first area operating in the same manner as the first L0 memory 120 a and a second area operating in a different manner from the first L0 memory 120 a. In this case, the first area and the second area do not necessarily coexist, but any one area may take up the entire first memory unit 2100 a.

Likewise, the second memory unit 2100 b may include a third area operating in the same manner as the second L0 memory 120 b and a fourth area operating in a different manner from the second L0 memory 120 b. In this case, the third area and the fourth area do not necessarily coexist, and any one area may take up the entire first memory unit 2100 a.

In this case, the ratio of the first area to the second area may be different from the ratio of the third area to the fourth area. However, the embodiment is not limited thereto. Therefore, the ratio of the first area to the second area may be the same as the ratio of the third area to the fourth area. In other words, the memory composition ratio in each memory unit may vary as desired.

In general, in the case of the conventional system-on-chip, the on-chip memory except for high-speed L0 memory was often composed of high-density, low-power SRAM. This is because SRAM has high efficiency in terms of chip area and power consumption relative to required capacity. However, with the conventional on-chip memory, the processing speed slowed down significantly as was inevitable in the case where tasks that require more data quickly than the predetermined capacity of the L0 memory, and, even when the need for the global memory is not great, there is no way to utilize the remaining global memory, resulting in inefficiency.

On the other hand, the shared memory 2000 in accordance with some embodiments may be controlled selectively by any one of the two controllers depending on the case. In the case depicted, the shared memory 2000 may be controlled not only as a whole by a determined one of the two controllers but also independently for each memory unit or each memory bank.

Through this, the shared memory 2000 in accordance with the embodiment can obtain an optimal memory composition ratio according to calculation tasks during the runtime and can perform faster and more efficient calculation tasks. In the case of a processing unit specialized in artificial intelligence, the required sizes of L0 memory and global memory may vary for each particular application. Moreover, even for the same application, the required sizes of L0 memory and global memory may vary for each layer when a deep learning network is used. In the shared memory 2000, in accordance with the embodiment, the composition ratio of the memory can be changed during runtime even when calculation steps change according to each layer, making fast and efficient deep learning tasks possible.

FIG. 16 is a diagram for illustrating the first memory bank of FIG. 15 in detail. Although FIG. 16 illustrates the first memory bank 2110 a, other memory banks may also have the same structure as the first memory bank 2110 a.

Referring to FIG. 16 , the first memory bank 2110 a may include a cell array Ca, a bank controller Bc, a first path unit P1, and a second path unit P2.

In this case, the bank controller Bc, the first path unit P1, and the second path unit P2 may be referred to respectively as a bank controller circuit, a first path unit circuit, and a second path unit circuit. However, for the sake of convenience, the terms are respectively unified as a bank controller, a first path unit, and a second path unit. In addition, the bank controller Bc, the first path unit P1, and the second path unit P2 may each be implemented as a circuit or circuitry.

The cell array Ca may include a plurality of memory devices (cells) therein. In the cell array Ca, the plurality of memory devices may be arranged in a lattice structure. The cell array Ca may be, for example, a SRAM (static random-access memory) cell array.

The bank controller Bc may control the cell array Ca. The bank controller Bc may determine whether the cell array Ca operates in the L0 memory type or in the global memory type, and may control the cell array Ca according to the determined memory type.

Specifically, the bank controller Bc may determine whether to transmit and receive data in the direction of the first path unit P1 or to transmit and receive data in the direction of the second path unit P2 during runtime. The bank controller Bc may determine a data transmission and reception direction according to a path control signal Spc.

The path control signal Spc may be generated by a pre-designed device driver or compiler. The path control signal Spc may be generated according to the characteristics of calculation tasks. Alternatively, the path control signal Spc may be generated by an input received from a user. In other words, the user may directly apply an input to the path control signal Spc in order to select optimal memory composition ratio.

The bank controller Bc may determine a path along which the data stored in the cell array Ca are transmitted and received via the path control signal Spc. The exchange interface of data may be changed as the bank controller Bc determines the path along which the data are transmitted and received. In other words, a first interface may be used when the bank controller Bc exchanges data with the first path unit P1, and a second interface may be used when the bank controller Bc exchanges data with the second path unit P2. In this case, the first interface and the second interface may be different from each other.

Address systems in which data are stored may vary as well. In other words, if a particular interface is selected, then read and write operations may be performed in an address system corresponding thereto.

The bank controller Bc may operate at a particular clock frequency. For example, if the cell array Ca is an SRAM cell array, the bank controller Bc may operate at the operating clock frequency of a general SRAM.

The first path unit P1 may be connected to the bank controller Bc. The first path unit P1 may directly exchange the data of the cell array Ca with the first processing unit 160 a. In this case, “directly” may mean being exchanged with each other without going through the global interconnection 6000. In other words, the first processing unit 160 a may exchange data directly with the first L0 memory 120 a, and the first processing unit 160 a may exchange data via the first path unit P1 when the shared memory 2000 is implemented logically in the L0 memory type. The first path unit P1 may include L0 memory controllers including the first L0 memory controller 122_1 a and the second L0 memory controller 122_1 b, as shown in FIG. 15 .

The first path unit P1 may form a multi-cycle sync-path. In other words, the operating clock frequency of the first path unit P1 may be the same as the operating clock frequency of the first processing unit 160 a. The first L0 memory 120 a may quickly exchange data at the same clock frequency as the operating clock frequency of the first processing unit 160 a in order to quickly exchange data at the same speed as the operation of the first processing unit 160 a. Likewise, the first path unit P1 may also operate at the same clock frequency as the operating clock frequency of the first processing unit 160 a.

In this case, the operating clock frequency of the first path unit P1 may be multiples of the operating clock frequency of the bank controller Bc. In this case, a clock domain crossing (CDC) operation for synchronizing the clocks between the bank controller Bc and the first path unit P1 is not required separately. Thus, a delay of data transmission may not occur. Accordingly, faster and more efficient data exchange can be possible.

In the embodiment shown in FIG. 16 , an operating clock frequency of the first path unit P1 may be 1.5 GHz, as an example. This may be twice the frequency of 750 MHz of the bank controller Bc. However, the embodiment is not limited thereto, and any operating clock frequency of the first path unit P1 may be possible as long as the first path unit P1 operates at integer multiples of the clock frequency of the bank controller Bc.

The second path unit P2 may be connected to the bank controller Bc. The second path unit P2 may exchange the data of the cell array Ca with the first processing unit 160 a not directly but via the global interconnection 6000. In other words, the first processing unit 160 a may exchange data with the cell array Ca via the global interconnection 6000 and the second path unit P2. In this case, the cell array Ca may exchange data not only with the first processing unit 160 a but also with other processing units.

In other words, the second path unit P2 may be a data exchange path between the cell array Ca and all the processing units when the first memory bank 2110 a is implemented logically in the global memory type. The second path unit P2 may include the global controller 2200 of FIG. 15 .

The second path unit P2 may form an asynchronous path or Async-Path. The operating clock frequency of the second path unit P2 may be the same as the operating clock frequency of the global interconnection 6000. Likewise, the second path unit P2 may also operate at the same clock frequency as the operating clock frequency of the global interconnection 6000.

In the case of the embodiment as shown in FIG. 16 , the operating clock frequency of the second path unit P2 may not be synchronized with the operating clock frequency of the bank controller Bc. In this case, the clock domain crossing (CDC) operation for synchronizing the clocks between the bank controller Bc and the second path unit P2 may be required. If the operating clock frequency of the bank controller Bc and the operating clock frequency of the second path unit P2 are not synchronized with each other, the degree of freedom in the design of the clock domain may be relatively high. Therefore, the difficulty of hardware design is decreased, thereby making it possible to more easily derive the desired hardware operation.

The bank controller Bc may use different address systems in the case of exchanging data via the first path unit P1 and in the case of exchanging data via the second path unit P2. In other words, the bank controller Bc may use a first address system if exchanging data via the first path unit P1 and a second address system if exchanging data via the second path unit P2. In this case, the first address system and the second address system may be different from each other.

A bank controller Bc is not necessarily required for each memory bank. In other words, a bank controller Bc may not be used to schedule, but instead serves to transfer signals, and thus, is not a required component for each memory bank having two ports. Therefore, one bank controller Bc can be operably coupled to control multiple memory banks. The multiple memory banks may operate independently even if they are controlled by the bank controller Bc. However, the embodiment is not limited thereto.

As a matter of course, the bank controller Bc may exist for each memory bank. In this case, the bank controller Bc may control each memory bank individually.

Referring to FIG. 15 and FIG. 16 , if the first memory unit 2100 a exchanges data via the first path unit P1, the first address system may be used. If the first memory unit 2100 a exchanges data via the second path unit P2, the second address system may be used. Similarly, if the second memory unit 2100 b exchanges data via the first path unit P1, a third address system may be used. If the second memory unit 2100 b exchanges data via the second path unit P2, the second address system may be used. In this case, the first address system and the third address system may be the same as each other. However, the embodiment is not limited thereto.

The first address system and the third address system may each be used exclusively for the first processing unit 160 a and the second processing unit 160 b, respectively. The second address system may be commonly applied to the first processing unit 160 a and the second processing unit 160 b.

In FIG. 16 , the operating clock frequency of the second path unit P2 may operate at 1 GHz, as an example. This may be a frequency that is not synchronized with the operating clock frequency of 750 MHz of the bank controller Bc. In other words, the operating clock frequency of the second path unit P2 may be freely set without being dependent on the operating clock frequency of the bank controller Bc at all.

A generic global memory has used slow SRAM (e.g., 750 MHz) and a global interconnection (e.g., 1 GHz) faster than that, inevitably resulting in delays due to the CDC operation. On the other hand, the shared memory 2000 in accordance with some embodiments has room to use the first path unit P1 in addition to the second path unit P2, thereby making it possible to avoid delays resulting from the CDC operation.

Furthermore, in the generic global memory, a plurality of processing units use one global interconnection 6000, and thus, when an amount of data transfer occurs at the same time, the decrease in the overall processing speed is likely to occur. On the other hand, the shared memory 2000 in accordance with some embodiments has room to use the first path unit P1 in addition to the second path unit P2, thereby making it possible to achieve the effect of properly distributing the data throughput that could be concentrated on the global controller 2200 as well.

FIG. 17 is a block diagram for illustrating a software hierarchy of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 17 , the software hierarchy of the neural processing device in accordance with some embodiments may include a deep learning (DL) framework 10000, a compiler stack 20000, and a back-end module 30000.

The DL framework 10000 may mean a framework for a deep learning model network used by a user. For example, a neural network that has finished training may be generated using a program such as TensorFlow or PyTorch.

The compiler stack 20000 may include an adaptation layer 21000, a compute library 22000, a front-end compiler 23000, a back-end compiler 24000, and a runtime driver 25000.

The adaptation layer 21000 may be a layer in contact with the DL framework 10000. The adaptation layer 21000 may quantize a neural network model of a user generated by the DL framework 10000 and modify graphs. In addition, the adaptation layer 21000 may convert a type of model into a required type.

The front-end compiler 23000 may convert various neural network models and graphs transferred from the adaptation layer 21000 into a constant intermediate representation (IR). The converted IR may be a preset representation that is easy to handle later by the back-end compiler 24000.

The optimization that can be done in advance in the graph level may be performed on such an IR of the front-end compiler 23000. In addition, the front-end compiler 23000 may finally generate the IR through the task of converting it into a layout optimized for hardware.

The back-end compiler 24000 optimizes the IR converted by the front-end compiler 23000 and converts it into a binary file, enabling it to be used by the runtime driver. The back-end compiler 24000 may generate an optimized code by dividing a job at a scale that fits the details of hardware.

The compute library 22000 may store template operations designed in a form suitable for hardware among various operations. The compute library 22000 provides the back-end compiler 24000 with multiple template operations required by hardware, allowing the optimized code to be generated.

The runtime driver 25000 may continuously perform monitoring during driving, thereby making it possible to drive the neural network device in accordance with some embodiments. Specifically, it may be responsible for the execution of an interface of the neural network device.

The back-end module 30000 may include an ASIC (application-specific integrated circuit) 31000, an FPGA (field-programmable gate array) 32000, and a C-model 33000. The ASIC 31000 may refer to a hardware chip determined according to a predetermined design method. The FPGA 32000 may be a programmable hardware chip. The C-model 33000 may refer to a model implemented by simulating hardware on software.

The back-end module 30000 may perform various tasks and derive results by using the binary code generated through the compiler stack 20000.

FIG. 18 is a block diagram for illustrating multi-processes of a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 18 , the neural processing system may create several processes Prs1 to Prs3 in an operation system OS. In this case, although FIG. 18 shows three processes, the embodiment is not limited thereto. That is, the number of processes may be two or fewer, or four or more as well.

Each process Prs1 to Prs3 may all be defined by the same context. In this case, a first process Prs1, a second process Prs2, and a third process Prs3 may each be separately allocated system resources from the operation system OS. Each of the first process Prs1, the second process Prs2, and the third process Prs3 may be an instance of a context, i.e., a program loaded into memory and executed.

In principle, each process may be executed in a separate address space, and resources may not be shared between the respective processes. However, the first process Prs1, the second process Prs2, and the third process Prs3 of the embodiment may be executed in the same address space depending on the type of data. As a matter of course, they may be executed in different address spaces depending on the type of data as well.

The first process Prs1, the second process Prs2, and the third process Prs3 may have virtual memory areas. Each of the virtual memory areas may have individually a code area, a data area, a heap area, and a stack area. In this case, the code area may refer to a space in which program functions written by users are stored, and the data area may refer to a space in which data used by programs, such as global variables or static variables, are stored. The heap area may refer to a memory area a programmer uses whenever needed. In addition, the stack area may refer to a space for temporarily storing addresses to be returned after execution of a called function and data such as local variables, parameters, return values, etc.

In this case, the virtual memory areas may be shared by the first process Prs1, the second process Prs2, and the third process Prs3, or may be independent of each other. This will be described in more detail later.

The first process Prs1 may include a first thread and a second thread. In this case, a thread may be a unit of a flow executed within a process. In other words, the first thread and the second thread may perform tasks in parallel while sharing the resources of a process. Although FIG. 18 shows two threads for each of the first process Prs1, the second process Prs2, and the third process Prs3, the embodiment is not limited thereto. That is, the number of threads in each process may be different from each other, and may be one or fewer, or three or more.

Each thread may be allocated a separate stack area. Each thread may share the code area, the data area, and the heap area.

FIG. 19 is a block diagram for illustrating address translation of a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 19 , the processing unit 160 may issue an instruction including a logical address LA for a task. At this time, the logical address LA may be translated into a physical address PA by a memory management unit MMU.

The logical address LA is a virtual address and may be different from the physical address PA, which is an actual address of the physical memory PM. The logical address LA may be mapped into the physical address PA. As the logical address LA is used, all addresses of the physical memory PM do not have to be paginated at once but can be paginated only when necessary. Further, space of the physical memory PM may also be saved by mapping a plurality of logical addresses LA to one physical address PA.

The memory management unit MMU may include a translation lookaside buffer 114 and a shared page table SPT. The translation lookaside buffer 114 may be included in the LSU 110 of FIG. 7 described above. The shared page table SPT may be located in an external memory, i.e., at least one memory out of the off-chip memory 30 of FIG. 2 , the shared memory 2000 of FIG. 3 , and the L2 shared memory 400 of FIG. 5 . However, the embodiment is not limited thereto. In this case, the memory management unit MMU may be referred to as a memory management circuit, but for the sake of convenience, the term is unified as memory management unit. Further, the memory management unit MMU may be implemented as a circuit or circuitry.

As described above, the translation lookaside buffer 114 may include information for translating recently used logical addresses LA into physical addresses PA. Accordingly, if the processing unit 160 issues an instruction including a logical address LA, it can be first checked whether the same logical address LA as the logical address LA of the issued instruction is stored in the translation lookaside buffer 114.

If the same logical address LA as the logical address LA of the issued instruction is stored in the translation lookaside buffer 114, this is a situation in which the translation lookaside buffer 114 is hit (TLB hit), and the logical address LA can be quickly translated into a physical address PA by the translation lookaside buffer 114. That is, the physical address PA is acquired via a first path R1, and the physical address PA of the physical memory PM can be accessed by the instruction.

The physical memory PM may include at least one physical page Pg0 to Pg(n-1). Although not all parts of the physical memory PM are paginated, the parts for the physical addresses PA mapped by the logical addresses LA may exist as physical pages Pg0 to Pg(n-1). The physical pages Pg0 to Pg(n-1) may all be allocated in the same size. The physical memory PM may be at least one of the off-chip memory 30 of FIG. 2 , the shared memory 2000 of FIG. 3 , or the L2 shared memory 400 of FIG. 5 , but is not limited thereto.

The memory management unit MMU may include the shared page table SPT. The shared page table SPT may include translation information of physical addresses PA for all logical addresses LA. In other words, the shared page table SPT may include mapping information for the logical addresses LA that are not stored in the translation lookaside buffer 114.

If the same logical address LA as the logical address LA of the issued instruction is not stored in the translation lookaside buffer 114, this is a situation that the translation lookaside buffer 114 is missed (TLB miss), and the logical address LA can be translated into the physical address PA by the shared page table SPT instead of the translation lookaside buffer 114. That is, the physical address PA is acquired via a second path R2, and the physical address PA of the physical memory PM can be accessed by the instruction.

In this case, the shared page table SPT may remain the same even if the process is switched. That is, in general, each process uses different addresses in memory and, accordingly, different page tables, but the neural processing device in accordance with the embodiment can use only one shared page table even when processes are switched.

The translation lookaside buffer 114 stores recently accessed addresses, and thus, can quickly guide access to frequently accessed physical addresses PA of the physical memory PM.

However, in a general device, while different page tables are used for each process, access to the physical address PA of the process used immediately before may become meaningless when process switching occurs. That is, the hit rate of the translation lookaside buffer may be significantly reduced.

In contrast, since the neural processing device in accordance with the embodiment uses a shared page table SPT and accesses via the same shared page table SPT even when process switching occurs, the hit rate of the translation lookaside buffer 114 is maintained so that memory access can be made efficiently.

FIG. 20 is a block diagram for illustrating allocation of physical pages of the physical memory of FIG. 19 .

Referring to FIGS. 19 and 20 , the shared page table SPT may include a page table entry (PTE) PTE in which the starting position of the physical address PA for each logical address LA is recorded, and mapping type data Md. The PTE may be used to calculate a physical address PA corresponding to a logical address LA.

The mapping type data Md may include information about mapping type of a logical address LA. The mapping type data Md may be, for example, data as to whether the mapping type is a shared type or a private type.

The shared type may be an address where data shared by all the respective processes in a multi-process environment are stored. Data stored in an address of the shared type may be stored in a shared physical page Psh in the physical memory PM. If there is a plurality of processes, for example, four processes of first to fourth processes, the shared physical page Psh may be a physical page shared by all of the first to fourth processes.

Since the shared physical page Psh stores the data shared by the respective processes in one physical page, the number of physical pages that was needed as many as the number of processes can be reduced to one, so that storage efficiency can be maximized.

In other words, data used by all the respective processes may be stored in the shared physical page Psh. In this case, the shared page table SPT may allow all processes to access the shared physical page Psh of the same physical address PA. At this time, the physical address PA of the shared physical page Psh may be equal to the value of PTE.

The private type may be an address for private data not shared by the respective processes with each other in a multi-process environment. Data stored in an address of the private type may be stored in a private physical page Ppr in the physical memory PM. The private physical page Ppr may allow each of the first to fourth processes to access different private pages.

That is, the respective processes may each store data in one private physical page Ppr. In this case, there may exist as many private physical pages Ppr as the number of a plurality of processes, i.e., as many as m. In other words, for example, if there are four processes, then there may be four private physical pages Ppr. That is, m may be the number of processes. In this case, the private physical pages Ppr may be arranged to be consecutive to each other.

Accordingly, for the private physical page Ppr, the physical address PA may be calculated by adding an offset according to each process ID to the value of the PTE. For example, in the first process, the physical address PA may be calculated according to the PTE value, and in the second process, the physical address PA may be calculated by adding an offset equal to the size of the physical page to the PTE value. In the third process, the physical address PA may be calculated by adding an offset equal to twice the size of the physical page to the PTE value. Likewise, in the fourth process, the physical address PA may be calculated by adding an offset equal to three times the size of the physical page to the PTE value.

FIG. 21 is a block diagram for illustrating allocation of physical pages of a physical memory of a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 21 , the mapping type data Md may be, for example, data as to whether the mapping type is a shared type, a private type, or an intermediate type.

The intermediate type may be an address for data shared by some processes with each other in a multi-process environment. Data stored in addresses of the intermediate type may be stored in intermediate physical pages Pitm in the physical memory PM. In the intermediate physical pages Pitm, some of the first to fourth processes may share the same page. For example, the first and third processes may share an intermediate physical page Pitm with each other, and the second and fourth processes may share an intermediate physical page Pitm with each other.

In this case, the first and second processes may be performed concurrently with each other, and thus, do not share the same intermediate physical page Pitm. Likewise, the third and fourth processes may be performed concurrently with each other, and thus, do not share the same intermediate physical page Pitm.

In other words, processes that share the same intermediate physical page Pitm with each other may be processes that do not operate concurrently with each other.

At this time, each of the concurrently operating processes that operate concurrently with each other may store data in different intermediate physical pages Pitm. In this case, there may exist as many intermediate physical pages Pitm as the number of concurrently operating processes, i.e., as many as k.

In other words, for example, if the first and second processes are processes operating concurrently with each other and the third and fourth processes are processes operating concurrently with each other, k may be two. Accordingly, two intermediate physical pages Pitm may be allocated. At this time, the intermediate physical pages Pitm may be arranged to be consecutive to each other.

Accordingly, for the intermediate physical page Pitm, the physical address PA may be calculated by adding a final offset according to each process ID to the value of the PTE. The final offset may be an offset for which concurrently operating processes have the same value as each other. For example, if the first and second processes are processes operating concurrently with each other and the third and fourth processes are processes operating concurrently with each other, the final offsets for the first and second processes may be 0, and the final offsets for the third and fourth processes may be the size of the intermediate physical pages Pitm.

For example, in the first process and the third process, the physical addresses PA may be calculated according to the PTE values, and in the second process and the fourth process, the physical addresses PA may be calculated by adding offsets equal to the sizes of the physical pages to the PTE values.

For the intermediate physical pages Pitm, a buffer width equal to the number of processes that do not operate concurrently is formed, and a process depth equal to a number of concurrently operating processes may be formed, i.e., as many as k.

FIG. 22 is a block diagram for illustrating allocation of physical pages of a physical memory of a neural processing system in accordance with some embodiments of the disclosure.

Referring to FIG. 22 , the mapping type data Md may be, for example, data as to whether the mapping type is a private type or an intermediate type.

In other words, there may be no physical pages shared by all processes, but private physical pages Ppr, which are physical pages dedicated to individual processes, and an intermediate physical page Pitm shared by some processes may exist in the physical memory PM.

Although there are no physical pages shared by all processes, intermediate physical pages Pitm can share data between some processes to increase data storage efficiency, and the hit rate of the translation lookaside buffer 114 can also be kept high by using a shared page table SPT.

FIG. 23 is a conceptual diagram for illustrating the mapping type data of FIG. 19 .

Referring to FIG. 23 , the mapping type data Md may be expressed in one of a shared type, a private type, and an intermediate type. In this case, the shared type may be, for example, an address where context data all of which are shared by one context are stored.

In contrast, the private type may be, for example, an address where the input/output data of each process are stored. Finally, the intermediate type may be an address where data that can be shared by some other processes are stored.

FIG. 24 is a conceptual diagram for illustrating deep learning calculations performed by a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 24 , an artificial neural network model 40000 is one example of a machine learning model and is a statistical learning algorithm implemented based on the structure of a biological neural network or is a structure for executing the algorithm, in machine learning technology and cognitive science.

The artificial neural network model 40000 may represent a machine learning model having an ability to solve problems by learning to reduce the error between an accurate output corresponding to a particular input and an inferred output by repeatedly adjusting the weight of the synapse by nodes. Nodes are artificial neurons that have formed a network by combining synapses, as in a biological neural network. For example, the artificial neural network model 40000 may include any probabilistic model, neural network model, etc., used in artificial intelligence learning methods such as machine learning and deep learning.

A neural processing device in accordance with some embodiments may implement the form of such an artificial neural network model 40000 and perform calculations. For example, the artificial neural network model 40000 may receive an input image and may output information on at least a part of an object included in the input image.

The artificial neural network model 40000 may be implemented by a multilayer perceptron (MLP) including multilayer nodes and connections between them. An artificial neural network model 40000 in accordance with the embodiment may be implemented using one of various artificial neural network model structures including the MLP. As shown in FIG. 29 , the artificial neural network model 40000 includes an input layer 41000 that receives input signals or data 40100 from the outside, an output layer 44000 that outputs output signals or data 40200 corresponding to the input data, and n (where n is a positive integer) hidden layers 42000 to 43000 that are located between the input layer 41000 and the output layer 44000 and that receive a signal from the input layer 41000, extract characteristics, and forward them to the output layer 44000. Here, the output layer 44000 receives signals from the hidden layers 42000 to 43000 and outputs them to the outside.

The learning methods of the artificial neural network model 40000 include a supervised learning method for training to be optimized to solve a problem by the input of supervisory signals (correct answers), and an unsupervised learning method that does not require supervisory signals.

The neural processing device may directly generate training data, through simulations, for training the artificial neural network model 40000. In this way, by matching a plurality of input variables and a plurality of output variables corresponding thereto with the input layer 41000 and the output layer 44000 of the artificial neural network model 40000, respectively, and adjusting the synaptic values between the nodes included in the input layer 41000, the hidden layers 42000 to 43000, and the output layer 44000, training may be made to enable a correct output corresponding to a particular input to be extracted. Through such a training phase, it is possible to identify the characteristics hidden in the input variables of the artificial neural network model 40000, and to adjust synaptic values (or weights) between the nodes of the artificial neural network model 40000 so that an error between an output variable calculated based on an input variable and a target output is reduced.

FIG. 25 is a conceptual diagram for illustrating training and inference operations of a neural network of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 25 , the training phase may be subjected to a process in which a large number of pieces of training data TD are passed forward to the artificial neural network model NN and are passed backward again. Through this, the weights and biases of each node of the artificial neural network model NN are tuned, and training may be performed so that more and more accurate results can be derived. Through the training phase, the artificial neural network model NN may be converted into a trained neural network model NN_T.

In the inference phase, new data ND may be inputted into the trained neural network model NN_T again. The trained neural network model NN_T may derive result data RD through the weights and biases that have already been used in the training, with the new data ND as input. For such result data RD, what training data TD were used in training and how many pieces of training data TD were used in the training phase may be important.

Hereinafter, a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure will be described with reference to FIGS. 19, 20, 26, and 27 . Any description overlapping with the embodiments described above will be omitted or simplified.

FIG. 26 is a flowchart for illustrating a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure, and FIG. 27 is a flowchart for illustrating accessing the physical memory of FIG. 26 .

Referring to FIG. 26 , a neural processing device refers to a shared page table in a first process and accesses the memory at S100.

Specifically, referring to FIG. 19 , the processing unit 160 may issue an instruction including a logical address LA for a task. At this time, the logical address LA may be translated into a physical address PA by a memory management unit MMU.

The memory management unit MMU may include a translation lookaside buffer 114 and a shared page table SPT. The shared page table SPT may include translation information of physical addresses PA for all logical addresses LA. In other words, the shared page table SPT may include mapping information for the logical addresses LA that are not stored in the translation lookaside buffer 114.

If the same logical address LA as the logical address LA of the issued instruction is not stored in the translation lookaside buffer 114, this is a situation in which the translation lookaside buffer 114 is missed (TLB miss), and the logical address LA can be translated into the physical address PA by the shared page table SPT instead of the translation lookaside buffer 114. That is, the physical address PA is acquired via a second path R2, and the physical address PA of the physical memory PM can be accessed by the instruction.

Referring again to FIG. 26 , the neural processing device determines whether there is process switching at S200. If so, the neural processing device refers to the shared page table in a second process and accesses the memory at S300). If not, the procedure ends.

Specifically, referring to FIG. 19 , the shared page table SPT may remain the same even if the process is switched. That is, in general, each process uses different addresses in memory and, accordingly, different page tables, but the neural processing device in accordance with the embodiment can use only one shared page table even when processes are switched.

In the following, step S100 or step S300 of FIG. 26 will be described in detail with reference to FIGS. 20 and 27 .

Referring to FIG. 27 , the PTE value and the mapping type are checked from the shared page table at S310.

Specifically, referring to FIGS. 19 and 20 , the shared page table SPT may include a page table entry PTE in which the starting position of the physical address PA for each logical address LA is recorded, and mapping type data Md. The PTE may be used to calculate a physical address PA corresponding to a logical address LA. The mapping type data Md may include information about the mapping type of a logical address LA.

Referring again to FIG. 27 , the neural processing device determines whether the mapping type is a shared type at S320. If so, a physical page is accessed according to the PTE value at S330.

Specifically, referring to FIGS. 19 and 20 , the mapping type data Md may be, for example, data as to whether the mapping type is a shared type or a private type. The shared type may be an address where data shared by all the respective processes in a multi-process environment are stored.

The shared page table SPT may allow all processes to access the shared physical page Psh of the same physical address PA. At this time, the physical address PA of the shared physical page Psh may be equal to the value of PTE.

Referring again to FIG. 27 , if the mapping type is not the shared type, the neural processing device accesses to a physical page by correcting the PTE value with a process ID as an offset at S340.

If the mapping type is not the shared type, the mapping type may be a private type. The private type may be an address for private data not shared by the respective processes with each other in a multi-process environment. There may exist as many private physical pages Ppr as the number of the plurality of processes, i.e., as many as m. In other words, for example, if there are four processes, then there may be four private physical pages Ppr. For the private physical page Ppr, the physical address PA may be calculated by adding an offset according to each process ID to the value of the PTE.

Hereinafter, a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure will be described with reference to FIGS. 19, 21, and 28 . Any description overlapping with the embodiments described above will be omitted or simplified.

FIG. 28 is a flowchart for illustrating a method for using a shared page table of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 28 , steps S310, S320, S330, and S340 may be the same as those in FIG. 27 . If the mapping type is not the shared type in step S320, the neural processing device determines whether the mapping type is a private type at S335. If so, it may proceed in the same way as step S340 of FIG. 27 .

If not, the neural processing device calculates a final offset according to the process ID at S350, and accesses to a physical page by correcting the PTE value with the final offset at S360.

Specifically, referring to FIGS. 19 and 21 , the mapping type data Md may be, for example, data as to whether the mapping type is a shared type, a private type, or an intermediate type. Therefore, if the mapping type is neither the shared type nor the private type, it may be an intermediate type.

For the intermediate physical page Pitm, the physical address PA may be calculated by adding a final offset according to each process ID to the value of the PTE. The final offset may be an offset for which concurrently operating processes have the same value as each other. For example, if the first and second processes are processes operating concurrently with each other and the third and fourth processes are processes operating concurrently with each other, the final offsets for the first and second processes may be 0, and the final offsets for the third and fourth processes may be the size of the intermediate physical pages Pitm.

For example, in the first process and the third process, the physical addresses PA may be calculated according to the PTE values, and in the second process and the fourth process, the physical addresses PA may be calculated by adding offsets equal to the sizes of the physical pages to the PTE values.

Hereinafter, a method for allocating a shared page table of a neural processing device in accordance with some embodiments of the disclosure will be described with reference to FIGS. 19, 20, and 29 . Any description overlapping with the embodiments described above will be omitted or simplified.

FIG. 29 is a flowchart for illustrating a method of allocating physical pages of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 29 , a neural processing device determines whether the mapping type is the shared type at S1100, and if so, allocates one physical page at S1200.

Specifically, referring to FIGS. 19 and 20 , the shared type may be an address where data shared by all the respective processes in a multi-process environment are stored. Since the shared physical page Psh stores the data shared by the respective processes in one physical page, the number of physical pages that was needed as many as the number of processes can be reduced to one, so that storage efficiency can be maximized.

Referring again to FIG. 29 , if the mapping type is not the shared type, the neural processing device allocates consecutive physical pages as many as the number of processes at S1300.

Specifically, referring to FIGS. 19 and 20 , the mapping type data Md may be, for example, data as to whether the mapping type is a shared type or a private type. Therefore, if the mapping type is not a shared type, it may be a private type.

There may exist as many private physical pages Ppr as the number of the plurality of processes, i.e., as many as m. In other words, for example, if there are four processes, then there may be four private physical pages Ppr. That is, m may be the number of processes. In this case, the private physical pages Ppr may be arranged to be consecutive to each other.

Hereinafter, a method for allocating a shared page table of a neural processing device in accordance with some embodiments of the disclosure will be described with reference to FIGS. 19, 21, and 30 . Any description overlapping with the embodiments described above will be omitted or simplified.

FIG. 30 is a flowchart for illustrating a method of allocating physical pages of a neural processing device in accordance with some embodiments of the disclosure.

Referring to FIG. 30 , steps S1100, S1200, and S1300 may be the same as those in FIG. 29 . If the mapping type is not the shared type in step S1100, the neural processing device determines whether the mapping type is a private type at S1250. If so, it may proceed in the same way as step S1300 of FIG. 29 .

If not, the neural processing device calculates a final offset according to the process ID at S1400, and allocates physical pages that are consecutive as many as the number of concurrently operating processes at S1500.

Specifically, referring to FIGS. 19 and 21 , the mapping type data Md may be, for example, data as to whether the mapping type is a shared type, a private type, or an intermediate type. Therefore, if the mapping type is neither the shared type nor the private type, it may be an intermediate type.

There may exist as many intermediate physical pages Pitm as the number of concurrently operating processes, i.e., as many as k.

In other words, for example, if the first and second processes are processes operating concurrently with each other and the third and fourth processes are processes operating concurrently with each other, k may be two. Accordingly, two intermediate physical pages Pitm may be allocated. At this time, the intermediate physical pages Pitm may be arranged to be consecutive to each other.

While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims. It is therefore desired that the embodiments be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than the foregoing description to indicate the scope of the disclosure. 

What is claimed is:
 1. A neural processing device including at least one neural processor, a shared memory shared by the at least one neural processor, and a global interconnection configured to exchange data between the at least one neural processor and the shared memory, comprising: at least one processing unit each of which included in each of the at least one neural processor and configured to provide logical addresses; a memory management unit configured to receive and translate the logical addresses into physical addresses; and a physical memory accessible by the physical addresses; wherein the memory management unit comprises a shared page table that has translation information between the logical addresses and the physical addresses and is shared by at least one process with each other; wherein the physical memory comprises a plurality of intermediate physical pages; wherein mapping types of the logical addresses comprise an intermediate type that is shared by some of the at least one process, a private type that is not shared by the at least one process, and a shared type that is shared by the at least one process; and wherein logical addresses of the intermediate type are configured to: allow the at least one process to access different intermediate physical pages of the plurality of intermediate physical pages if the at least one process is performed concurrently; and allow the at least one process to access a same intermediate physical page of the plurality of intermediate physical pages if the at least one process is not performed concurrently.
 2. The neural processing device of claim 1, wherein the shared page table comprises: a page table entry (PTE) having recorded therein starting positions of the physical memory corresponding to the logical addresses; and mapping type data having recorded therein the mapping types of the logical addresses; wherein the mapping type data is data about one of the shared type, the private type, or the intermediate type.
 3. The neural processing device of claim 1, wherein the physical memory further comprises a shared physical page; and wherein logical addresses of the shared type allow all of the at least one process to access a same shared physical page in the physical memory.
 4. The neural processing device of claim 3, wherein context data of a context to which the at least one process belongs are stored in the shared physical page.
 5. The neural processing device of claim 1, wherein the physical memory further comprises a plurality of private physical pages; and wherein logical addresses of the private type allow each of the at least one process to access different private physical pages of the plurality of private physical pages in the physical memory.
 6. The neural processing device of claim 5, wherein the private physical pages are arranged to be consecutive to each other.
 7. The neural processing device of claim 5, wherein each of the private physical pages stores input/output data of each of the at least one process.
 8. The neural processing device of claim 1, wherein the plurality of intermediate physical pages are arranged consecutively.
 9. The neural processing device of claim 1, wherein the memory management unit further comprises a translation lookaside buffer configured to store physical addresses for recently used logical addresses.
 10. The neural processing device of claim 9, wherein the translation lookaside buffer: translates a stored logical address into a physical address for the stored logical address if a logical address that is same as the stored logical address is received; and translates a received logical address into a physical address for the received logical address by referring to the shared page table if a logical address that is not same as the stored logical address is received.
 11. The neural processing device of claim 9, wherein each of the at least one neural processor comprises at least one neural core; and each of the at least one neural core comprises: one of the at least one processing unit; an L0 memory configured to transmit and receive data to and from the one of the at least one processing unit; and a load store unit configured to load data into the L0 memory and transmit data from the L0 memory.
 12. The neural processing device of claim 11, wherein the load store unit comprises the translation lookaside buffer. 